The invention relates to a charged particle beam apparatus for making a sliced specimen to be observed by a transmission electron microscope (TEM).
In recent years, as miniaturization of a pattern of a semiconductor device proceeds, importance of technology of observing and evaluating a particular minute portion of the semiconductor device using a Transmission Electron Microscope (TEM) increases. In order to fabricate a sliced specimen to be such particular minute portion, a focused ion beam apparatus is widely used, however, there arises a problem of damage by a focused ion beam as the required thickness of the specimen becomes thinner, and a method for preventing damage is needed.
As the solution for the above state, for example, a method of irradiating a gas-ion beam using an element whose chemical activity is low such as argon as ionic species is proposed (refer to Patent document 1). Since an argon ion milling apparatus which is widely used at present is a dedicated device having a single function, positional relation between the specimen and the ion beam is a simple, an irradiation angle of the ion beam can be easily set by setting a tilt of a specimen stage, and arrangement is instinctively comprehensible. However, when the actual sliced specimen is inclined or bending with respect to the stage, the specimen cannot be recognized, therefore, there was a problem that it was difficult to precisely control the irradiation angle. An incident angle is an important parameter which affects an etching rate and the like, therefore, accurate incident angle control has been required.
On the other hand, an apparatus incorporating a mechanism of irradiating a gas-ion beam such as argon with the focused ion beam apparatus is also proposed (for example, refer to Patent document 2). In such composite apparatus, the irradiation angle of the argon-ion beam is fixed in a parallel movement or in a rotation direction with respect to an axis of the focused ion beam or a scanning electron microscope, for convenience of processing, observation and so on. Accordingly, an installation angle of the mechanism of irradiating the argon-ion beam has to be an angle not parallel, or not orthogonal to the rotation axis of the stage. In this case, as an example is shown in FIG. 2, a rotation angle 14 of the specimen stage is not equal to an incident angle 13 of the beam 12 to a specimen surface. Therefore, it is difficult to instinctively comprehend the incident angle of the argon-ion beam with respect to the surface of the specimen 2. It is necessary to perform stage operation by calculating a required movement amount of the stage for the irradiation at the desired angle. It is required to solve the problem from viewpoints of operational efficiency and of occurring man-caused mistakes.
[Patent document 1] JP-A-10-221227
[Patent document 2] JP-A-6-2601129
In view of the above, an object of the invention is to provide a charged particle beam apparatus capable of controlling an irradiation angle of a gas-ion beam accurately and easily according to an arrangement state of a sliced specimen.